Hydraulic circuit apparatus



April 30, 1946.

| c. ROTTERETAL 2,

HYDRAULIC CIRCUIT APPARATUS 4 Sheets-Sheet 1 Filed March 15, 1944 Patented Apr. 30, 1946 HYDRAULIC CIRCUIT APPARATUS Lutwin C. Rotter, Maplewood, and Victor G. Klein, St. Louis, Mo., assignors to Lincoln Engineering Company, St. Louis, Mo.,' a corporation of Missouri Application March 13, 1944, Serial No. 526,160

10 Claims.

This invention relates to hydraulic circuit apparatus, and with regard to certain more specific features, to high-pressure apparatus of this class,

Among the several objects of the invention may be noted the provision of hydraulic apparatus and the hydraulic circuit formed thereby for commercially producing extremely high unit pressures (for example 25,000 p. s. i.) for hydraulic testing purposes, and liquid supplies for hydraulic presses, hydraulic machine tools and the like; the provision of apparatus and a circuit of the class described which will quickly produce said pressures in cases where high bulk factors exist in the apparatus requiring the pressures; the provision of apparatus of this class which will hold'the stated high pressure indefinitely even with leakage in the apparatus served; and the provision of means of the class described which is reliable, compact, safe and fool-proof, and which will remain so over a long life. Other objects will be in part obvious and in part pointed out hereinafter. a

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In-the accompanying drawings, in which is illustrated one of various possible embodiments of the invention,

Fig, 1 is a side elevation of apparatus embodying the invention;

Fig. 2 is an enlarged top plan view of Fig. 1;

Fig. 3 is a fragmentary: front elevation (viewed from the right of Figs. 1 and 2) drawn on the scale of Fig. 2;

Fig. 4 is an enlarged, detailed plan View of a valve control block, being viewed substantially from line 4-4 of Fig. 3;

Fig. 5 is a horizontal section through said control block, being taken on line 5-5 of Fig. 3;

Fig. 6 is a left-side elevation of Fig. 4., being viewed from line 6--6 on Fig. 4; I

Fig. 7 is a horizontal sectional view of a control valve, being taken substantially on line 'l-l of Fig. 3;

Fig. 8 is' a vertical section taken through a high-pressure pump element,'t he section being taken on line 8-8 of Fig. 3;

Fig. 9 is an enlarged detail section of an outlet check valve assembly for a high pressure pump;

Fig. 10 is a circuit diagram.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

The hydraulic system and apparatus of the present invention is adapted commercially to produce a high working pressure (up to 25,000 p. s. i.) operating from a low pressure air supply- (of the order of 100 p. s. i.). This end is attained without any substantial danger of explosion and at high volumetric capacity. a

Referring now more particularly to Figs. 1-3, there isshown at numeral 1 a framework supporting a tank 3. The latter carries liquid up to a level such as shown at L in Fig. 3. The exact level is not important, since it is primarily the measure of the amount of fluid carried in the tank (40 lbs., for example). The liquid may be oil or light grease. At the bottom of the tank is an outlet connection 5 which through a T 1 has one branch 9 leading to a solid steel highpressure distributor and control block H. The other branch of the T 1 leads to a drain cock I 3 which is normally closed but which may be opened for drainage and charging of the tank, and for removing sedimentation of solids, or moisture due to condensation.

Above the liquid level L the tank 3 carries air, an inlet 15 being provided for its introduction. This inlet is connected by a branch pipe Hi to an air header I1. Another branch 2| leads from the header l1 to the inlet of a first reciprocating air engine 23. A third branch 25 from the header [1 leads to a second reciprocating air engine 21, In the branch line 25 is a manually controlled regulator valve 29 and a suitable pressure gauge 3|.

The header 11 receives its air through a threeway valve 33 from an air inlet line 35. The air line 35 carries air pressure at, for example, 100 p. s. i. pressure. This is an ordinary value available from many air compressor supply units. The valve 33 (Figs. 3 and 7) has an exhaust outlet 31. and a rotary plug 39 in which is a threeway port 4!. Plug 39 is operated by handle 60. In the position of the valve plug shown in Fig. 7 air may pass from the supply pipe 35 to the header ll. By rotating the plug counterclockwise, the air supply may be cut off and the header I! connected with the exhaust 31. Thus by opening the valve 33 air may be supplied to the tank 3 above the liquid therein at p. s. i. It is also supplied at that same pressure to the first air engine 23 and to the second engine 21 at that or a. lower pressure, as determined by the regulator 29.

Each air engine 23 and 21 is of the general type disclosed in United States Patents 2,215,852 and 2,269,423, dated September 24, 1940, and January 13, 1942, respectively. Further description it is believed will be unnecessary in view of the showing in these patents, except to state (see Fig. 10) that engines 23 and 21 have reciprocating, double-acting, air-operated pistons 24 and 28 respectively to which air is distributed for double action by means of valve gears 43 and 44 respectively. The total pressure exerted by each piston under a given air pressure is proportional to its area. The area of the piston of engine 23 is smaller than that of the piston of engine 21.

The piston 24 of engine 23is connected to the plunger I6 of a well type of hydraulic pump indicated broadly at 45. The pump 45 extends down to a point near the bottom of the tank 3, where it has its inlet check valve I8 always submerged for all normal variations in the level L. Associated with plunger I6 is a valve 29. Pumps'of this class operated by air engines similar to 23 are known and will not be further described (see, for example, United States Patent 1,970,591, dated August 21, 1934). The outlet of the pump is indicated at 49. Thisoutlet is connected by means of pipe with the control block II. The piston of air engine 21 is connected to the piston of a hydraulic booster pump indicated broadly at 4?, the details of which are shown in Fig.8.

Details of the control block I I are shown in Figs. 4-6. It consists of a solid steel piece in which is an outlet manifold 53 to which is connectedan outlet pipe or service connection 55. This pipe 55 is connected with the device or machine to which liquid pressure and volume is to be supplied, which may be a device to be tested for high pressure, or a hydraulic press or other machine. This control block has an inlet passage 51 to which is connected the line 9 leading from the liquid tank 3. In a cross passage 6| is a new type of check valve 59 especially adapted to the high pressures involved.

This valve consists in a cylindric counterbore G3 in passage 6| at the bottom shoulder 55 of which counterbore is seated a disc 61 having openings 69. This disc is recessed as shown at H for producing a ledge 13. This ledge 13 provides the seat for the endmost of a series of accurately made ring seats 15, each of which seats endwise on another and each of which has an interior conical opening 11 rounded at its small end as shown at 19. Accurately seating balls 8! are carried within the conical openings 11. These, under unbalanced pressure from 53 to 51 rest upon the seats. Under unbalanced pressure from 51 to 53, they unseat. A gland nut 83 serves to press together disc 61 and the ring seats 15. Nut 83 is counterbored as indicated at 85 and provided with openings 81 to the counterbore so that fluid may flow from inlet 51 through the valve 59 to the outlet 55, unseating the balls 8| as it does so. However, the balls are limited in unseating movements by the disc 61. The spacev between the endmost ball and the disc 61 is less than the movement of the balls which would bring about reclosing of the balls on the rounded ends 19 when opened.

Passing through the nut 83 is a threaded, rotary, operating stem 89, packed as indicated at 9| and having a nose portion 53 which may contact the lowermost one of the balls 8|. A cross pin 95 prevents the stem 89 from being unthreaded too far. Outside, the stem 89 carries a crank handle 91 and between it and the nut 83 is a tubular spacer 99 which permits the operator to screw the stem forward only enough to -cause unseating of the balls 8I without pressing the endmost one into engagement with member 61.

The counterbore 63, disc 61, ring seats 15 and balls 8| are made to a high degree of accuracy including lap fits where necessary to prevent leakage. The balls and the conical seats 11 are arranged so that upon closing the valve, the upper ball seats first, then the second, third and fourth successively. Upon opening the valve the lowermost ball opens first and then the others in serial order, the upermost opening last. The advantage of such a construction is that as the endmost ball comes to a seat under high pressure, all of them gradually exert increased throttling action without all seating at once. This reduces the cutting action of fluid in passing between the balls and the seats. When the balls open, the upper one unseats last, the others being already open in serially increasing order.

At numeral IUI is shown another valve similar to the one just described in which like numerals designate like parts. The holding nut I03 for this valve difiers from the nut 83 in that it has no operating stem through it. This valve IOI is in a passage I05 which leads to the outlet manifold 53.

A passage I01 is connected through the openings 81 to the inside of the nut I03. It is this passage I01 on the inlet side of the valve IN, to which is connected the pipe 5| from the pump 45. This passage I01 is also connected by means .ofa pipe I09 to the inlet III of the booster pump 41 above mentioned (Fig. 8). The plunger of this pump is shown at [I3 and is connected with the piston 28 of the reciprocating air engine 21.

The outlet II5 of the pump 41 is connected to the outlet passage 53 in the block II. A special outlet check valve H1 is used in pump 41 and consists in a threaded thimble II9 counterbored as shown at I2I to receive a series of closely dimensioned rings I23 having oppositely countersunk openings I20 therethrough. Balls I25 are trapped in the spaces left by the countersinks and seat on the bottoms of openings I20 in a direction to allow flow from the pump but to resist back flow of fluid to the pump. Milled slots 50 prevent the balls from seating on the upper ends of openings I20 when flow is outward from I23. Each ring has a ledge I22 at one end for telescoping with a shoulder I24 of its neighbor. Copper packing washers I3I are used between the ledges I22 and shoulders I24. The last ring toward the pump telescopes a recess I26 and seats on a copper washer I28. The last ring in the other direction seats on a copper washer I28 in the bottom of the counterbore IZI. Axial pressure from threading home the thimble I I9 seals together all of the rings I23.

Fig. 10 will aid in followingthe operation which is as follows, assumin that the tank 3 has been filled up to the level L with suitable liquid. Crank 91 is backed ofifrom the position shown in Fig. 5 to allow valve 59 to operate automatically. The necessary connection with the apparatus to be. supplied with pressure is madethrough line 55. Air at 100 p. s. i. or so is supplied from the pipe 35 and the valve 33 is opened as indicated in Figs. '1 and 10. This supplies air at 100 p. s. i. onthe surface of the liquid in the tank 3. It also supplies air at this pressure to the air engine 23 and air under pressure to the engine 21. The regulator 29 is set foran air pressure which when Operatin on the booster pump 41 will produce the ultimate hydraulic pressure desired in line 55.

Pressure ofair on the liquid in the tank 3 quickly forces it out in volume to the inlet 51 of the block The pressure automatically opens the valve 59 and flow occurs through the outlet manifold 53 to the supply line 55. This quickly fills the apparatus to be tested even though it has a high bulk factor. This is because the displacement of air into tank 3 and displacement of liquid therefrom may be quite fast.

- At the same time the engine 23 starts automatically due to the air pressure supplied to it. This reciprocates the pump 45 which draws fiuid from the bottom of the tank and forces it out through the line 5 I. Thus it is delivered to port I01 in the block H, from whence it passes through the check valve to the outlet 53 and also to the line 55.

When, due to filling up of the apparatus connected with 55, the reaction pressure in the pipe 55 becomes greater than the unit pressure on the liquid in the tank 3 (100 p. s. i.), the valve 59 automatically closes and the pump 45 con tinues-to supply pressure through the valve |0|. The pump 45 and engine 23 are capable (for example) of running the pressure up to 2,000 p. s. i. Pump 45 may be considered to be a primer pump. The pressure of 2,000 p. s. i. is determined by the relative areas of the engine piston and pump plunger.

During the operating period above described, the engine 21 has also received air and has been operating its pump 41 which supplies fluid at the I connection H5 of the block Thus this pump 41 also supplies fluid to the outlet manifold 53 and hence to the pipe 55. The pump 41 receives its supply from the primer pump 45 via pipe 5|, port I01, line I09 and port I. The area of the piston in engine 21 and the area of its pump plunger are so related that pump 41 generates about 25,000 p. s. i. hydraulic pressure. Thus, as the reaction pressur in line 55 builds up past the 2,000 p. s. i. value of pump 23 the valve |0| also closes and thereafter the pipe 5| from pump 45 supplies only the pump 41 via line I09. Pump 41 at all times acts as a booster pump for the primer pump 45. Thus the pump 41 continues to build up pressure, both valves 59 and |0| being closed, until the pressure in the line 55 reaches the stated value of about 25,000 p. s. i. The exact value is determined by the setting of th regulator 29 which controls the unit air pressure applied to the piston of the engine 21.

At this point it will be clear why the valves 59 and IOI need to be of improved construction. No ordinary check valve would be able'to last long under a pressure difference between 25,000 p. s. i. in the manifold 53 and the 100 p. s. i. in the port 51 (in the case of valve 59); nor the pressure difference between 25,000 p. s. i. and the 2,000 p. s. i. inthe port I01 (in the case ofvalve IN).

The engines 23 and 21 automatically stop when the pumps 45 and 41 respectively reach pressures of 2,000 p. s. i. and 25,000 p. s. i. For example, the ratio of areas of the pistons in engine 23 and pump 45 is 20:1, thus producing from 100 lbs. air pressure approximately 2.000 p. s. i. In the case of the booster engine 21, the ratio of its piston area to the area of the plunger H3 in pump 41 is 370:1 which gives a margin for ad- .iusting down the air pressure at regulator 29 and still obtaining 25,000 p. s. i. or better in the outlet of pump 41. When the pumps stall (as they will when their plunger pressures balance the'respective air engine pressures) the high pressure will be maintained in the outlet 55 even though leakage should occur. This is because as soon as the outlet pressure drops, this imbalances the hydraulic pressure with respect to the air pressure on the piston of engine 21 whereupon the latter again starts to bring the hydraulic pressure back up. When engine 21 starts, engine 23 also starts because therequirements of pump 41 incipiently drop the pressure in line 5|.

Upon the completion of a. testing or operating cycle, the three-way air valve 33 is moved to its exhaust position, thus exhausting air from the pressure tank and from the engines 23 and 21. The crank 91 is then rotated to the position shown in Fig. 5 againstthe limiting stop 99. This opens the check valve '59 and hydraulic fluid bleeds back throughthe check valve 59 and returns to the pressure tank. I

The present invention is an improvement over prior schemes for the purpose, since it introduces an intermediate-pressure filling operation after a low-pressure filling operation and before the highest pressure is applied. Thus not only does it take care of. bulk factor due simply to the requirements of volumetric filling, but bulk factor (due to stretching undersubstantial pressure) of the physical parts of the system, including the apparatus served. Loss of time is avoided that would. be involved intaking up the last-mentioned bulk factor by means ofv the ultimate highpressure application. In other. words, the air pressure in tank 3'quick1y causes filling 0f the system, the intermediate-pressure primer pump quickly stretches the physical parts of the system. under the 2,000 lbs. pressuraand the booster pump completes the high-pressure application. If the higher pressure booster pump 41 were to operate alone throughout the pressure range that the intermediate-pressure pump now does, the time required for a cycle of operation would be much longer due. to the necessarily low volumetric displacement of pump 41.

The apparatus issafe, since no pressures higher than p. s. i. or so are applied to the tank 3.

Itis to be understood that, although air ressure is used, other gases under pressure may be employed and the terms air and gas are to be understood as being synonymous. Also other liquids besides oil may be employed, such as hydraulic brake fluid, water, alcohol, all being equivalents for the purpose of the invention.

Under the provisions of Rule 43 of the U. S. Patent Office, attention is hereby called to-applicants application, Serial Number 588,452, filed April 16, 1945, for Hydraulic circuit apparatus.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

l. A hydraulic circuit comprising a sump tank carrying liquid and air, a service connection, a first liquid line connecting the sump tank to the service connection, a check valve in said first line opening downstream from the tank, a second liquid line connecting said sump tank and the servioe connec i n and ha n ss n aid first line and its check valve, a pump in iscid second liquid l a c eck valve -.between;s -id 'numnand sa d service line, a third liquid line connecting between said service connection-and a point in the se ond lin l cated between said numpi nd said second check valve and bvipassing the latter, and .a pump in said third l ine.

,2. A hydraulic circuit comprising a sump tank carrying liquid and air under relatively low pressure, a relatively high-pressure service line, a relatively low-pressure liquid line connecting the sum tank with the service line, a check valve in said first line opening downstream from the tank, a second liquid line under relatively intermediate pressure connecting said sump tankand theservice line and by-passing said first line and its check valve, apump of intermediate pressure in said second liquid line supplying said intermediate pressure, a check valve between said pump and said service line, athird relatively high-pressure liquid line connecting :between said service connection and a point in the second line located between saidpump and said second check valve and by-passing the latter, and a relatively high-pressure pump in said :third .line and supplying said relatively high pressure.

3. A hydrauliccircuit comprising a sump tank carrying liquid and air under relatively low pressure, a relatively high-pressure service line, a relatively low-pressure liquid line connecting said sump tank with the service line, a check valve in said first line opening downstream from the tank, a second line under relatively intermediate pressure connectingsaid sump-tank and the service line and by-passing said first line and its check valve, a pump of intermediate pressure in said second liquid line, a check valve between said pump and said service line, a third relatively high-pressure liquid line connecting between said service line and a point in the second line located between said pump and said second check valve and by-passing the latter, and a relatively high-pressure pumpin -said third line, both of said pumps being of the reciprocating plunger variety, reciprocating-piston air engines respectively driving saidpumps, the piston-plunger area ratio of the pump in the second line being smaller than the corresponding piston-plunger ratio of the pump in the third line, and air connections supplying relatively low-pressure air to the tank and both of said engines,the liquid pressure produced by the air in the sump tank being less than the liquid pressure produced by either of said pumps.

4. A hydraulic circuit comprising a sump tank carrying liquid and air under relatively low pressure, a relatively high-pressure service line, a relatively low-pressure liquid line connecting said sump tank with the service line, a check valve in said first line opening downstream from the tank, a second line under relatively intermediate pressure connecting said sump tank and the service line and by-passing said first line and its check valve, a pump of intermediate pressure in said second liquid line, a check-valve between said pump and said service line, a third relatively high-pressure liquid line connecting between said service connection and a point in the second line located between aid pump and said second check valve and by-passing the latter, and a relatively high-pressure pump in said thirdline, both of said pumps being of the reciprocating plunger variety, reciprocatingepiston air engines respectively driving said pumps, the piston-plunger area ratio of the pump in the second line being smaller than the corresponding piston-plunger ratio of the pump in the third line, air connections supplying relatively low-pressure air to the tank and both of said engines, and an air pressure regulator individually controlling air pressure to the engine of the pump in the third line.

5. A hydro-pneumatic circuit comprising a sump tank carrying liquid and air, a high-pressure service connection, a low-pressure line connecting the sump tank with the service connection and carrying liquid, a check valve in said low-pressure line opening downstream from the tank, a second liquid line connecting said sump tank and the service connection and by-passing said first line and its check valve, a first pump in said second liquid line, a check valve between said pump and said outlet connection, a third liquid line between said outlet connection and a point located between said pump and said second check valve and by-passing said second check valve, a second pump in said third line and primed by said first pump, air engines for the pumps, air supply means for the sump tank and the pump engines, and release valve control means associated with the air supply means for simultaneously controlling and releasing the air sup y to said tank and pump engines.

6. A hydro-pneumatic circuit comprising a sump tank carrying liquid and air, a high-pressure service connection, a low-pressure line connecting the sump tank with the service connection and carrying liquid, a check valve in said lowpressure line opening downstream from the tank, a second liquid line connecting said sump tank and the service connection and by-passing said first line and its check valve, a first pump in said second liquid line, a check valve between said pump and said outlet connection, a third liquid line between said outlet connection and a point located between said pump and said second check valve and by-pa-ssing said second check valve, a second pump in said third line and primed by said first pump, said second pump being capable of producing a higher liquid pressure at a given air pressure to its engine than is the first pump with the same or higher air pressure to its engine.

7. A hydro-pneumatic circuit comprising a sump tank carrying liquid and air, a high-pressure service connection, a low-pressure line connecting the sump tank with the service connection and carrying liquid, a check valve in said low-pressure line opening downstream from the tank, a second liquid line connecting said sump tank and the service connection and by-passing said first line and its check valve, a first pump in said second liquid line, a check valve between said pump and said outlet connection, a third liquid line between said outlet connection and a point located between said pump and said second check valve and by-passing said second check valve, a second pump in said third line and primed by said first pump, air engines fOr the pumps, air supply means for the sump tank and the pump engines, release valve control means associated with the air supply means for simultaneously controlling and releasing the air supply to said tank and pump engines, said second pump being capable of producing a higher liquid pressure at a given air pressure to its engine than is the first pump with the same or higher air pressure to'its engine.

*8. A hydro-pneumatic high pressure circuit comprising a sump tank carrying a liquid and air, a high pressure service connection, a low pressure line connecting the sump tank with the service connection and carrying liquid, a first automatic check valve in said first low pressure line opening downstream from the tank, a second liquid line connecting said sump tank and the service connection and by-passing said first line and said check valve, an air-operated priming pump in said second liquid line, a second automatic check valve between said pump and said service connection, a third liquid line between said service connection and a point located between said priming pump and said second check valve and lay-passing said second check valve, an airoperated booster pump in said third line, and manual means for opening said first-named automatic check valve.

9. A hydro-pneumatic high-pressure circuit comprising a sump tank carrying liquid and air, a high-pressure service connection, a high-pressure distributor and control block, a low-pressure line connecting the sump tank with the service connection through said block and carrying liquid, a firstcheck valve in said block and located in said low-pressure line and opening downstream from the tank, a second liquid line connecting said sump tank and the service connection through said control block and bypassing said first line and its check valve, a primer pump in said second liquid line, a second check valve in said second line and located in said block and being between said pump and said service connection, a third liquid line between aid service connection and a point in said block located between said primer pump and said sec- 0nd check valve and Icy-passing said second check valve, a booster pump in said third line, and manual means for opening said first-named check valve, said manual means being associated with said block.

10. A hydro-pneumatic circuit comprising a sump tank carrying liquid and air, a high-pressure service connection, a low-pressure line connecting the sump tank with the service connection and carrying liquid, a check valve in said first low-pressure line opening downstream from the tank, a second liquid line connecting said sump tank and the outlet connection and bypassing said first line and its check valve, an airo erated pump in said second liquid line, a check valve between said pump and said service connection, a third liquid line between said service connection and a point located between said intermediate pressure pump and said second check valve and icy-passing said second check valve, and a high pressure air-operated booster pump in said third line, common means for delivering air under pressure to said sump tank and to both of said air-operated pumps, and an exhausting air-control valve associated with said air supply means for controlling application and release of pressure simultaneously to said sump tank and both airoperated pumps.

LUTWIN C. ROTTER. VICTOR G. KLEIN. 

